1. Field of the Invention
The instant invention relates to methods of and apparatus for monitoring transients in low inductance circuits and to a probe utilized to practice said method and apparatus. More particularly, the instant invention relates to methods of and apparatus for monitoring low inductance circuits, wherein the low inductance circuits include a pair of flat cable transmission lines. The instant invention is further directed to a probe for use in monitoring pairs of flat cable transmission lines.
2. Technical Considerations and Prior Art
Computers and other electronic equipment are sensitive to transient voltages and currents which can cause malfunctions. Accordingly, there is a need to constantly monitor circuits for high current transient waveforms. Conventional methods for measuring high current transient waveforms associated with low inductance circuits, such as those associated with capacitor discharge units, either utilize current viewing resistors which introduce unwanted ground points or require passing current to be measured through a current viewing transformer, which results in the introduction of unwanted additional inductance into the circuit. Low inductance, high current circuits often use flat cable transmission lines, which when surrounded by a magnetic core carrying an auxiliary winding introduce substantial additional impedance in the circuits.
The prior art includes a number of patents directed to monitoring circuits for transients. However, all of these patents have deficiencies when used to monitor transients in low inductance, high current circuits using flat cable transmission lines. For example, U.S. Pat. Nos. 3,876,911; 4,424,512; and 4,438,403 each use reed switches to monitor circuits for transient spikes. However, none of these patents provide an analog output and all of these patents are limited to rather low frequencies of operation and therefore do not effectively respond to frequencies greater than one kilohertz. U.S. Pat. No. 4,180,775 is directed to transient current measurement; however, the device disclosed in this patent does not produce an analog time response. U.S. Pat. Nos. 3,697,911 and 4,012,703 disclose printed circuit configurations; however, neither of these patents suggest that the printed circuit configurations are of interest with respect to configuring pick-up coils, which coils are capable of monitoring flat cables without introducing extra impedance into the circuit of which the flat cable is a component.
In view of the aforementioned considerations, there is a need for a device to enable measurement of high current transient waveforms associated with low inductance circuits such as those used with capacitor discharge units, wherein the device neither introduces an unwanted ground point, nor additional inductance into the circuit being measured.